Greg, using that logic we should just use LCD displays for everything and not bother with nixies.... :)
Ha ha. On Tue, Jan 7, 2025 at 3:25 PM gregebert <[email protected]> wrote: > Attaching the datasheet I found online. > > As far as shortening the count, pull the CLR pin low. Since the CLR pin is > a TTL-level input, and the outputs are open-collector, you will need to use > a diode to protect TTL-level inputs if you drive them from any of the > open-collector outputs. The diode is connected such that the cathode is > connected to the open-collector output, and the anode goes to the TTL input > along with a pullup resistor to +5V. These counters also support cascading, > which makes it a ripple-counter. Anyone who has done logic design knows (or > *should* know....) decoding ripple-counter outputs will produce glitches, > so you cant use those for clocks or resets to other chips. > > You also have to be careful about the anode supply voltage; if it's too > low you wont get reliable nixie-tube ignition. If it's too high, you will > cause breakdown at the 74142 outputs, which will cause unwanted cathodes to > glow. This is a TTL part, so you wont damage the output from excessive > voltage *as long as the current is limited*. The breakdown mechanism in > NPN transistors is similar to zener diodes (thru a reverse-biased PN > junction), and it's not destructive like CMOS devices where the oxide gets > irreparably destroyed by overvoltage. I would set the anode voltage to a > point where the voltage across the 74142 measures around 45 volts with a > DMM. The anode supply is going to be around 180V depending upon the voltage > drop across the nixie tube. > > I would only build this as a novelty; there are far-better and cheaper > ways to do this with modern ICs. > > On Tuesday, January 7, 2025 at 1:39:12 PM UTC-8 Leroy Jones wrote: > >> Well I know that saw a reference to some old RCA data sheet application >> note regarding the unobtainium 74142 chip. >> It's ok fine with me if that never turns up because I have figured out >> how to work with these 74142 chips to effectively shorten their counts >> for 10's of seconds, 10's of minutes, 10's of hours counters on a >> clock. However, if such application note does actually exist and can be >> found, >> it might shed some light on alternate methods used to manage the >> count-shortening on these 74142 decade counter/nixie driver ICs. >> I am currently scrounging around everywhere for any and all information I >> can find about 74142. Thanks everyone for your help and responses so far! >> >> >> >> >> On Tuesday, January 7, 2025 at 3:09:10 PM UTC-5 J Forbes wrote: >> >>> Reading David's post from 2012, my understanding is that he built a CMOS >>> nixie clock in 1976, using 4033 chips, and the schematic in the 1974 RCA >>> databook. That databook covers CMOS and Linear chips, not TTL. >>> >>> So, I think you're chasing a ghost, caused by a slight misunderstanding. >>> >>> >>> On Tuesday, January 7, 2025 at 12:14:04 PM UTC-7 Leroy Jones wrote: >>> >>>> Yes, thank you gentlemen for the responses to my inquiry regarding the >>>> rare and esoteric 74142 decade counter/nixie driver IC. >>>> I have successfully built a fully operational clock using them. It >>>> was not easy nor practical. But it works. This clock uses (17) ICs. >>>> I am seeking the supposed ancient RCA application note which reportedly >>>> describes a clock design that utilizes these 74142 ICs. >>>> The very existence of this app. note is in and of itself somewhat of an >>>> urban legend. Am I chasing a ghost here? >>>> >>>> But many will ask "why bother doing it?"..............To which I >>>> answer: "because it's cool" >>>> >>>> >>>> >>>> >>>> On Tuesday, January 7, 2025 at 11:41:04 AM UTC-5 gregebert wrote: >>>> >>>>> There was a T4142 TTL IC that has a binary counter and nixie driver in >>>>> one device; the Texas Instruments datasheet was published in 1972. Good >>>>> luck finding these devices; I've seen a few for sale online and I'm >>>>> certain >>>>> very few were manufactured because LED displays quickly killed-off nixies >>>>> around that time. >>>>> >>>>> There is a short thread on neonixie from 2012: >>>>> https://groups.google.com/g/neonixie-l/c/R7K9eJcP8h0 >>>>> >>>>> >>>>> On Monday, January 6, 2025 at 5:00:49 PM UTC-8 J Forbes wrote: >>>>> >>>>>> There's the TI applications for the 74141 driver and 7490/92 counter, >>>>>> but that's probably not what you want. >>>>>> >>>>>> http://selectric.org/nixie/ticlock.gif >>>>>> >>>>>> >>>>>> >>>>>> On Monday, January 6, 2025 at 4:53:36 PM UTC-7 Leroy Jones wrote: >>>>>> >>>>>>> Does anyone here remember ever seeing any application notes about >>>>>>> making a nixie tube clock based around the 74142 counter/driver IC? I >>>>>>> seem to recall a post made many years ago by David Forbes where he >>>>>>> referred >>>>>>> to an old RCA application note about this. >>>>>>> >>>>>>> Any info will be greatly appreciated. >>>>>>> >>>>>>> Chuck >>>>>>> >>>>>> -- > You received this message because you are subscribed to the Google Groups > "neonixie-l" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion, visit > https://groups.google.com/d/msgid/neonixie-l/89a17e21-3184-4653-aa21-92bdef24fadfn%40googlegroups.com > <https://groups.google.com/d/msgid/neonixie-l/89a17e21-3184-4653-aa21-92bdef24fadfn%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. 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